The lifespan of a Christmas tree depends on several factors, including the species of tree, how it was grown and maintained, and how it is cared for after being harvested. On average, a Christmas tree can last for up to two to four weeks, provided that it is properly hydrated and maintained during the holidays. To ensure a longer lifespan, it's important to monitor the water level and keep the tree away from heat sources, as these can cause the tree to dry out and wither more quickly.